Born Cassius Marcellus Clay, Jr. in Louisville, KY, he was introduced to boxing by police officer Joe E. Martin after the latter encountered an irate, 12-year-old Ali seeking retribution for a stolen bicycle. Martin trained the young man in the fundamentals, which led to an impressive amateur career that netted six Kentucky Golden Glove titles and two national Golden Globe wins before he claimed the Light Heavyweight Gold medal at the 1960 Summer Olympics in Rome. Upon his return to the United States, Ali began his unprecedented professional career, amassing a record of 19-0, with 15 knockouts, between 1960 and 1963. Ali stood out from his peers by virtue of his physicality and his personality. A tall heavyweight at 6'3," he nevertheless relied on astonishing speed and footwork to dazzle his opponents, who would weaken under a dizzying array of jabs before succumbing to expertly placed body and head punches.Ali backed up his talent with a public persona, dubbed the "Louisville Lip," that combined winning charm with wild, often rhyming boasts about which round he would knock out his next opponent and their physical weakness in the face of his agility, strength and "beauty." He borrowed the practice from the famed wrestler "Gorgeous" George Wagner, who would also whip audiences into a frenzy over his ringside theatrics. Ali's transformation from over-the-top personality to genuine sports legend began in 1964 with his bout against reigning heavyweight champion Sonny Liston. The fight was expected to deflate Ali's boundless ego, but in an astonishing turn of events, he defeated the hulking Liston through his astonishing speed, even after being temporarily blinded by a foreign substance. Liston threw in the towel in the seventh round, making Ali the youngest boxer to take a title from a reigning heavyweight until Mike Tyson defeated Trevor Berbick in 1986. The triumph, however, was short-lived; the National Boxing Association stripped him of his title when he agreed to a 1965 rematch against Liston, which was further marred by allegations that Liston had deliberately lost the fight.Ali was no stranger to controversy at this point. He had begun associating with Malcolm X and the Nation of Islam as early as 1961, and announced his membership with the organization immediately after the first Liston fight. He was initially known as Cassius X before the Nation's leader, Elijah Muhammad, announced that the fighter would now be known as Muhammad Ali. The champ's association with Muhammad was an even greater dividing point among boxing fans than his early boasts; the Nation of Islam was regarded as an extremist organization that was believed to preach hatred of whites, and Ali himself was an outspoken opponent of interracial marriage. The conversion cast a pall over Ali for many boxing aficionados, and he would have to literally fight for his life and reputation over the next few years to win their approval.After defeating Floyd Patterson in a technical knockout in 1965, he worked his way through a series of European bouts before returning to America in 1967 for a title fight against WBA champ Ernie Terrell. The battle saw Ali taunting his opponent with cries of "Uncle Tom" and subjecting him to 15 punishing rounds, which many sports analysts observed as retribution for Terrell backing out of the fight a year before. The bout ended with a technical win, but again, the victory was short-lived. That same year, he refused to join the Army on the grounds that he was a conscientious objector against the Vietnam War, and was summarily stripped of his title and boxing licenses from various states. Ali was found guilty of committing a felony, and was forced to support himself through speaking engagements at colleges across the country. He also appeared in the short-lived Broadway musical "Buck White" (1969), and made a singing appearance on "The Ed Sullivan Show" (CBS, 1948-1971) with the show's cast.The year 1970 saw Ali's boxing license restored in Georgia, which began the second and greatest chapter in his professional life. Growing public antipathy towards the Vietnam War caused several boxing commissions and state Supreme Courts to reverse their decision against Ali, and he soon began brawling his way back to the heavyweight crown. His ascension did not take the easy route. In 1971, he was defeated by Joe Frazier before a capacity crowd at Madison Square Garden, and Ken Norton broke his jaw in a 1972 fight for the NABF Heavyweight title. But he soon defeated both opponents in non-title bouts in 1973 and 1974, respectively, and set Ali up to claim the Heavyweight crown in a 1974 fight against champion George Foreman in Zaire, Africa.The fight, elevated to mythic levels by promoter Don King, was titled "The Rumble in the Jungle," and saw an invigorated Ali returning to 1960s-era levels of confidence and verbal dexterity as he publicly eviscerated Foreman. However, the majority of the press, including Ali's greatest supporter and foil, Howard Cosell, believed that he could not defeat the stunningly powerful Foreman, who had dropped both Frazier and Norton in the second rounds of their respective fights. But Ali remained unmoved, and his confidence and sheer physical grace inspired the people of Zaire to rally behind him. In turn, he provided them with a fight worthy of the warrior-kings of their heritage; Ali hoodwinked Foreman into wearing himself down, first by laying punishing hits into the startled champ, and later, by pretending to fall back against the ropes in exhaustion. In doing so, he was able to withstand Foreman's best punches while stitching him with an array of carefully chosen headshots. The ruse, later called "the rope-a-dope," exhausted Foreman, and Ali unleashed a dizzying volley of hits that dropped the champion in the eighth round. The "Rumble in the Jungle" became one of the greatest fights in the history of boxing, and was the subject of an Oscar-winning documentary, "When We Were Kings" (1996), as well as the docudrama "Don King: Only in America" (1997), with Ving Rhames as King and Darius McCrary as Ali.The following year, Ali stunned fight fans by nearly losing to an obscure brawler named Chuck Wepner, who knocked down the champ in the ninth round. Ali came back to pummel Wepner into submission in the 15th round, but the David-and-Goliath story would inspire an unknown actor named Sylvester Stallone to base a boxing script called "Rocky" (1976) on the climatic fight. The Wepner bout was soon forgotten after King launched "The Thrilla in Manila," which would pit Ali against Joe Frazier for the third time. Ali baited his opponent in the press for months prior to the match, which drove Frazier into a fit of anger. Over the course of their 14-round fight in the Philippines, much of which took place in temperatures over 100 degrees, Ali and Frazier came close to claiming victory, but Ali was named the victor after Frazier was unable to answer the bell for the 15th round. That same year, Ali converted from the Nation of Islam to Sunni Islam.By this point in his career, Ali was nothing less than a global sports icon. His feats had been celebrated in books, magazine articles, and even songs like "Black Superman (Muhammad Ali)" (sic) by Johnny Wakelin and the Kinshasa Band. Ali was even the star of his own biopic, "The Greatest" (1977), which followed his career from the Olympics to the Rumble in the Jungle, and provided the voice for his animated counterpart in a Saturday morning cartoon, "I Am the Greatest: The Adventures of Muhammad Ali" (NBC, 1977). The following year, he fought Superman in DC Comics' "Superman vs. Muhammad Ali." However, the real Ali was beginning to show all-too-human signs of age and wear from decades of boxing.Though he continued to defeat fighters both great and obscure, including Ken Norton in a match at Yankee Stadium in 1976, Ali was winning more fights by decision than knockout. He was also physically brutalized in an exhibition match against wrestler and martial artist Antonio Inoki, who fought the champion to a draw largely through kicking Ali throughout the 15-round match. Ali suffered from blood clots and infection in his legs, which resulted in a decrease of his storied speed and agility. In 1978, the beginning of the end came with Ali's loss to Olympic champion Leon Spinks. Expecting an easy fight against an untried newcomer, Ali was battered by the seemingly tireless Spinks until the latter was declared winner in a 15-round decision. The façade of invulnerability had fallen for Ali, but like so many times before, he came from behind to reclaim the title, as well as the record as the first three-time world heavyweight champion, from Spinks in September of that year. In June of 1979, Ali announced his retirement.Ali remained in the spotlight in the months following his retirement, appearing in commercials for D-Con Roach Proof and other products, and even taking another stab at acting in "Freedom Road" (NBC, 1979), a historical biopic of Gideon Jackson, an ex-slave who was elected to the U.S. Senate, as well as on episodes of "Diff'rent Strokes" (NBC/ABC, 1978-1986) and "Vega$" (ABC, 1978-1981). But the lure of the ring - in particular, an $8 million purse to fight Larry Holmes - was too strong, and in 1980, he agreed to meet the powerful contender at Caesar's Palace in Las Vegas. The fight was an ill-advised move for the 39-year-old Ali, whose health had already begun its precipitous decline. His fight doctor, Ferdie Pacheco, had left Ali's camp after receiving a medical report that showed the fighter's kidneys in a state of near-collapse. A 1980 MAYO Clinic report prior to the Holmes fight showed that he had also lost basic hand-eye coordination and was displaying slurred speech. His pre-fight training was marked by heavy fatigue, which was exacerbated by large doses of a thyroid medicine that left him overheated but unable to perspire. This shadow of Ali's former self took a tremendous beating from Holmes in Las Vegas before Angelo Dundee, his longtime trainer, called off the fight in the 11th round. It was the first time Ali had ever lost a fight by anything other than a decision.There would be one final time in the ring for Ali, against an up-and-comer named Trevor Berbick in 1981, which ended in a loss by unanimous decision after 10 rounds. This ignominious finale was largely eclipsed by news in 1984 that Ali had been diagnosed with Parkinson's syndrome, the result of the severe head trauma that many boxers endure in their career. The disease racked his body with tremors and reduced his powerful voice to a whisper, but it left his spirit and mind intact, and for the next 30 years, Ali would lend his name to a variety of humanitarian causes which, in turn, underscored the global notion that Ali was more than just a sports figure, but a true hero and a cultural icon for all nations. In 1987, Ali was selected by the California Bicentennial Foundation for the U.S. Constitution to personify the ideals of that document, as well as that of the Bill of Rights, at various public functions. Ali was among the few civilian figures to visit Iraq during the first Gulf War, and actually met with then-dictator Saddam Hussein to negotiate the release of American workers held hostage during its early days. By 1993, Ali had been named along with Babe Ruth as the most recognized athlete in America out of a list of 800. The study also showed that 97 percent of Americans over the age of 12 knew Ali.In 1996, a visibly trembling Ali defied the physical constraints of his body to light the torch at the 1996 Summer Olympics in Atlanta, GA. That same year, George Forman aided his former combatant to the dais to accept the Academy Award for "When We Were Kings" (1996), which won Best Documentary at the Oscars. Sports Illustrated, which named him "Sportsman of the Year" three times during his career, bestowed the title of "Sportsman of the Century" in 1999. His life and accomplishments continued to serve as the basis for features, including Leon Ichaso's "Ali: An American Hero" (Fox, 2000); "King of the World" (ABC, 2000), with Terrance Howard as Ali; and Michael Mann's epic biopic "Ali" (2001), which earned Will Smith an Oscar nomination for his vibrant portrayal of the champion. The following year, Ali returned to the Middle East to serve as a U.N. Messenger of Peace in Afghanistan.In 2005, Ali's humanitarian efforts were rewarded with the Presidential Citizens Medal and the Presidential Medal of Freedom from President George W. Bush. That same year, his $60 million non-profit Muhammad Ali Center opened in Louisville. The center served as a repository for his boxing memorabilia and a focal point for his efforts to enhance themes of responsibility and personal growth among visitors. In 2007, he received an honorary doctorate from Princeton University as part of the school's 260th anniversary. That same year, he was listed second, behind the legendary Joe Louis, as the greatest heavyweight of all time by ESPN. The 2009 documentary "Facing Ali" featured interviews with many of his most formidable opponents, including Foreman, Joe Frazier, Leon Spinks, and Larry Holmes, each of whom discussed their history-making bouts with Ali. A documentary about his Vietnam-era draft fight, "The Trials of Muhammad Ali" (2013) was released to critical acclaim. His memoir, The Greatest: My Own Story was published in 2015 and edited by no less imposing a cultural figure than Pulitzer and Nobel Prize-winning novelist Toni Morrison. Ali, in severe physical decline for years due to advanced Parkinson's Disease, was the subject of multiple death rumors in his later years. He died at his home near Phoenix, Arizona on June 3, 2016, days after being admitted to the hospital with respiratory problems. He was 74 years old.